Balancing machine



Dec. 12, 1944. J, J. GUEST BALANGING MACHINE Filed Dec. 16, 1945 Patented Dec. l2, 1944 vUNITED sTATEs PATENT oFElcE nmotlem i y' Application. December. 16, 1943, Serial No.,'514,553. v In Great Britain September 25,1942

This invention relates to.meanswforsupporting and controlling the motion of a frame upon which, in particular, rotors are mounted in order that they maybe tested for thecorrections necessary to render them in` balance. The frame is rstly carried on the supporting partorxbase so that `its only possiblemotions `are those in which every point of it -moves parallel to a certain plane or suiciently closely thereto, `herein termed planar motion. An object of the invention is to provide in a testing machine of the above character` a plurality of taut flexible members xed to thestationary baseand extending a spaced' distancefrom and substantially parallel to the plane of the frame, one of thev .flexible members disposed` longitudinally and `another transversely of the framepwith `means for connecting the frame to either of the` rflexible members to restrain planar movement of the frame parallel to ythe flexible member to which it is connected.

This planar motionofthe frame maybe effected in` any knovvmmanner; thepreferred manner, however, `isto connect the frametothe supporting baseby three or :more parallel` andy sufficiently exibleinembers. These members may be in tension, when merely hinged rods or cords in/the manner of trilar suspension would serve, ,or-in compression andyactingeby their flexibility, `the control for small .movements such as are to be used, then giving a `sufliciently closeplanar movement to the frame. In thevpreferred apparatus the supporting members, either tension or compression; actl bytheir. flexibility and give anelastic` determination of the position of equilibrium,

which maybefurther determined by other spring fittings added to control 'the natural period of vibration of the frame. These supporting members,vvhich maybe of any section, are preferably rmly connected at their ends tothe frame and to the base. sothat the frame moves underi the flexibility of the supports only, and even such friction as occurs in rolling is eliminated. The supports are such that their axial strains produce insignicant effects. 1

These supporting members may be arranged in any manner. In a convenient construction the frame may be regarded as having a flat horizontal upper surface intended to carry the rotor with its axis horizontal and parallel to the length of the frame, which frame may be of a rectangular shape and supported at each corner, with intermediate supports if desirable. In the following description it will be convenient to regard the construetion as being thus, but actually any relatively equivalent arrangement may be used.

The invention yWill be `better understood from `the following. detailed-,description considered in `The arrangement is'shownin Figures '1, 2 and l 3., ,in which the frame.r .'I` is shown, supported: on the base 2 byfour elasticsupports, 3, 4, 5 and 6, one at each-corner, acting inJcom-pression. The support members are ofequal length for convenience andconnetpoints inone plane in theframe to points inl one plane in the base, both theseplanes` being horizontal. f .For small. movements, then,4

the frame Amoves with planar motion WithinV in- Sgnicant amounts. The rotor R toI be tested issupportedV in bearings l and 8 carriedy on the frameQwithits aXisAl-A horizontal and parallel to the side 0f` the frame. In the operation of. testing, the rotorrevolvesbut as-this does not cause any appreciable tendency' to` displacement of the frame inthe direction of the `axis; .AI-A, restraint against motionin this direction is not actually necessary. Nevertheless, it is desirable that the framesh'ouldbeso restrained. This restraint here is termedthe axial.control, and when effected it leaves the. frame with tWo degrees ofv freedom,A one of :which is removed by a further restraint, termed the final control.

These controls consist, in limiting vthe motionof a selected point of theframe toone line, Whichbl.

course will be horizontal as regards this description. The limitation may be effected in any knownmanner. Preferably the construction is as follows: Av flexible Wire 9 is'h'eld at its two ends at points Ill` and II in the base-or in brackets.

thereon, and at an intermediate point Vl2' is attached to the frame, or to a bracket thereon so that, the wire 9 being tight, the point at which it is attached to the frame is prevented from moving in the direction of the Wire, except for exceedingly small movements, but is capable of small but much larger movements perpendicular to this line by virtue of the elasticity of the wire. `In the restraint above referred to, the wire 9 is set parallel to the axis of the rotor and, as limiting movement of the frame in the axial direction, is thus the axial control. As mentioned above, it is not absolutely necessary and so may sometimes be omitted for reasons of cheapness or simplicity.

As there is no great tendency to motion axially, suilicient restraint against such movement can sometimes be given by making the supports of a section having greater resistance to bending in the direction A-A than in a perpendicular direction, and in this case, if the supports are of suitable stiffness, the primary control previously described may be omitted.

The frame having thus an axial control ofl either type, it is subjected to a further restraint, again conning the motion of a point on the frame to a (here horizontal) line and again by any known means but preferably by the means above described. Such a final control is shown in the iigures where a iiexible strip I3 is fastened to the base at the points I4 and I5 and to the frame at the point IE. This control is shown as arranged in a machine for dynamic balancing and is set with the strip perpendicular to the axis of the rotor so that the movement of the point I6 in a direction perpendicular to the axis of the rotor is prevented. It is thus termed a cross-control. The only appreciable motion of the frame remaining is that of rotation about a line perpendicular to the planar motion of the frame (a vertical line as described), ypassing through the intersection of the flexible elements in the plan view; that is, through the point in which elements 9 and I3 coincide as shown in Figure 3.

For dynamic balancing it is frequently convenient that the frame can have alternative rotation about some other axis parallel to this axis, and to this end a second such final control Il is arranged perpendicular to the rotation axis. This cross-control may be fitted so that the position of the point xed along the axis may be adjusted or so that it is fixed in position. In the figures, one control-thatl of point IIi-is shown as xed and another is shown as adjustable. The second cross-control comprises a strip I `I fastened to the base at I8 and I9 and to the frame at 20. As only one of the nal cross-controls I3 and I'I is in use at one time, they are arranged to be easily released, the intermediate connection to the frame being merely a clamp.

In a machine intended for both static and dynamic balancing, a further final control 2l is provided, preferably of the same type, with the strip set parallel to the strip 9 of the primary control. The strip 2| is shown connected to the base at 22 and 23 and to the frame at 24. When the machine is used for dynamic balancing this termediate clamp; when it is used for static balancing, the controls for the dynamic balancing quate control in machines for static balancing only can sometimes be provided by making the supporting members of sufficient lateral rigidity in the A-A direction so that no other control is then necessary, every point of the frame being adequately constrained to move perpendicular to the line A-A with suflicient accuracy.

In a complete machine, the frame carries the rotor R by bearings in brackets arranged to adjust along Ways formed on the frame so that its axis is co-linear with the axis of the apparatus 25 for determining the mass-radius-length correction necessary and its phase. Suitable means are provided for driving the rotor and the connected apparatus 25.

Obviously various changes in the form, construction, arrangement and combination of the several parts of my new apparatus may be made and substituted for those herein shown and described without departing from the nature and principle of my invention as set forth in the following claims.

I claim:

1. A machine for testing the balance of rotors and the like comprising a frame adapted to support the rotor to be tested with its axis disposed parallel to the plane of the frame, a, stationary base, stily flexible supports extending from the base for supporting the frame for substantially planar movement parallel to the base, a plurality of taut flexible members extending a spaced distance from and substantially parallel to the plane of the frame, one of said flexible members disposed longitudinally and another of said flexible members disposed transversely of the frame, means for securing the ends of the flexible. members to the base, and means for connecting the lframe to either of the flexible members at an intermediate point thereof to restrain planar movement of the frame in a direction parallel to the exible member to which it is connected.

2. A machine for testing the balance of rotors and the like comprising a frame adapted to support the rotor to be tested with its axis disposed parallel to the plane of the frame, a stationary base, means for supporting the frame for substantially planar movement parallel to the base, a plurality of taut flexible members extending a spaced distance from and substantially parallel to the plane of the frame, one of said flexible members disposed longitudinally and another of said exible members disposed transversely of the frame, means for securing the ends of the iiexible members to the base, and means for connecting the frame toeither of the flexible members at an intermediate point thereof to restrain planar movement of the frame in a direction parallel to the flexible member to which it is connected.

JAMES JOHN GUEST. 

